Managed care for mental health and substance abuse ("behavioral health") services has become common over the past decade. Utilization management, including gatekeeping arrangements and subsequent review, is one major approach to containing costs and ensuring appropriate care. Despite widespread use and controversy regarding utilization management practices, little is known about its effects on outpatient specialty mental health services. This study will analyze the effects of expanding direct access to outpatient specialty mental health care in an HMO. The research design is quasi-experimental, taking advantage of a natural experiment in which a subset of enrollees experienced this change in access. The HMO removed stringent gate-keeping requirements and routine utilization management activities for the first 8 outpatient specialty behavioral health visits. Using an internal comparison group that had started out with a similar system of direct access to specialty mental health care, the study will analyze the effects of the changes on initial access, utilization level and patterns, quality indicators, and cost of outpatient specialty mental health service. Subgroups of particular interest include patients with depression, and children and adolescents. Data sources are claims/encounter data and eligibility files for 1996-1999. Descriptive and multivariate techniques will be used to study these effects. This study will make a valuable contribution to our understanding of how utilization management of outpatient specialty behavioral health care affects initial access, patterns of care, quality indicators, and costs for these services. The results will inform health plan decision-makers and others as they make utilization management choices that may have a major impact on patients and enrollee populations overall.